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-   -   Turbulence and viscosity of non-Newtonian Fluids (http://www.cfd-online.com/Forums/fluent/38608-turbulence-viscosity-non-newtonian-fluids.html)

David November 14, 2005 09:00

Turbulence and viscosity of non-Newtonian Fluids
 
Hello, I use fluent and need to simulate polymer viscosity vs shear rate and the turbulence. I've try with some turbulent models but they want constant viscosity to calculate the turbulence.

Is it possible to copy the non newtonian model in a UDF and then use a turbulent model. I've never try to use UDF until now.

Thank you for advice

David

HVN November 14, 2005 10:17

Re: Turbulence and viscosity of non-Newtonian Flui
 
To use turbulence with non-newtonian fluid, you need to activate the turbulence model through the command line not through the GUI.

So to resume, you doesns't need to use UDF for your problem.

David November 16, 2005 10:26

Re: Turbulence and viscosity of non-Newtonian Flui
 
I wrote

define/models/viscous/turbulence-expert/turb-non-newtonian?

but the command is not valide. I received this message "invalid command".

Thanks

Wael November 16, 2005 10:52

Re: Turbulence and viscosity of non-Newtonian Flui
 
What version of Fluent do you have? in 6.0.12 the command is not available.

David November 17, 2005 05:08

Re: Turbulence and viscosity of non-Newtonian Flui
 
The version is Fluent 6.2.16.

Is it possible to check if I have all the libraries to use the turbulence with the viscosity of non newtonian fluids.

Wael November 17, 2005 05:39

Re: Turbulence and viscosity of non-Newtonian Flui
 
Hi David, First select the standard k-e model, then use TUI and write define\model\viscous\turbulent expert\ Then you can select

turb-non-newtonian? Enable turbulence for Non-Newtonian fluids.

non-newtonian-modification? Enable Non-Newtonian modification for Lam-Bremhorst model.

Hope that can help - Wael

David November 17, 2005 12:23

Re: Turbulence and viscosity of non-Newtonian Flui
 
Thank you a lot.

I use it with non newtonian power law.


Zahra November 29, 2005 08:09

Re: Turbulence and viscosity of non-Newtonian Flui
 
I wanted to define viscosity by this function:

v=v0*exp(b(T-T0))*g^n where : v=viscosity b=constant T=temperatur g=shear rate

thanks for you kind help


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